St. Isaac's Cathedral in St. Petersburg has been one of the city's most famous landmarks for 150 years. Its gilded dome has become a symbol of modern Petersburg architecture. In terms of size, this Orthodox cathedral ranks fourth in the world, surpassed only by St. Peter's Basilica in Rome, St. Paul's Cathedral in London, and Santa Maria del Fiore in Florence.

The grandeur of the cathedral is confirmed by its dimensions: the height is 101.5 meters, the length is 111.3 meters, the width is 97.6 meters, and the external diameter of the dome is 25.8 meters. The building is surrounded by 112 columns, each reaching 17 meters in height and weighing 114 tons at the lower level.

The history of St. Isaac's Cathedral began in 1706 when, by the order of Peter I, a wooden church was built for the Admiralty, consecrated in honor of St. Isaac of Dalmatia. In 1717, Peter commissioned architect Georg Friedrich von Matarran to replace the wooden walls with stone. However, in 1735, lightning caused a fire, and construction was abandoned.

The third attempt to build the cathedral was made by Catherine II, who commissioned Antonio Rinaldi for the construction. However, due to illness, the architect returned to Italy, and Vincenzo Brenna continued the work at the behest of Emperor Paul. In 1816, the collapse of the ceiling plaster required a major renovation of the building.

Emperor Alexander I decided to completely rebuild the cathedral and announced a competition for a new project in 1809. The project by French architect Auguste Montferrand won. Construction began in 1818 and lasted 40 years under three emperors: Alexander I, Nicholas I, and Alexander II. Delays were caused by various factors, including calculation errors and difficult terrain conditions. For the foundation, 11,000 piles were driven in and two rows of granite blocks were laid. Columns weighing 114 tons were delivered from Finland.

Montferrand began installing the columns before the walls were erected. The first column was raised in 1822, and the last one eight years later. The dome, with a diameter of 26 meters, was covered in gold three times. The cathedral was consecrated on June 11, 1858.

The interiors of the cathedral resemble a luxurious palace. Marble, malachite, lapis lazuli, and other precious materials were used for decoration. The altar is designed as a stained glass window depicting the 'Risen Christ.' The interiors cover 4,000 square meters and include 103 paintings and 52 artworks. Among the artists are Karl and Fyodor Bryullov, Fyodor Bruni, and Pyotr Basin.

The cathedral is the second tallest dominant feature in Petersburg. From the colonnade at a height of 43 meters, a panorama of the city opens up. The ascent is made via a spiral staircase with 262 steps.

More than 400,000 people worked on the construction. For the foundation, granite blocks weighing up to 114 tons were quarried in Karelia. The gilding of the domes required 100 kg of gold, which led to the death of 60 people from mercury vapors.

After the October Revolution, the cathedral was nationalized and became a museum-reserve. In 1931, the State Anti-Religious Museum with a Foucault pendulum was opened here. In 1937, the cathedral received the status of a monument, and after the war, it continued to function as a museum.

Since 1990, services have resumed in the cathedral. It is managed by the State Museum-Preserve 'St. Isaac's Cathedral,' which also includes the Church of the Resurrection of Christ and the Chapel-Museum of the Savior on Spilled Blood. The museum collection includes paintings, sculptures, mosaics, and rare books. Tours are conducted daily, except on Wednesdays.

St. Isaac's Cathedral is open for visits from 10:30 AM to 6:00 PM, except on Wednesdays. The colonnade is accessible without breaks from 10:00 AM to 6:00 PM and from 6:00 PM to 9:30 PM. Services are held daily, except on Wednesdays, and admission is free.